Vitamin e, vitamin c, and beta-carotene act as which may reduce the risk of heart disease, cancer, arthritis, and alzheimer's disease.

The correct answer is "antioxidants".

Vitamin E, vitamin C, and beta-carotene act as antioxidants by increasing the turnover of reduced glutathione (by the use of vitamin C) or by acting directly against oxidants (such as free radicals or superoxides and hydrogen peroxide). These free radicals exert oxidative stress in vulnerable tissues such as those in coronary arteries wherein it promotes atherosclerosis and plaque formation and in cancer by promoting multiple DNA mutations. By the action of these vitamins, these diseases may be prevented.